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E-1
Chapter 1
Chapter 5
Chapter 3
Chapter 7
Chapter 9
Chapter 2
Chapter 6
Chapter 4
Chapter 8
A
ppendices
A P P E N D I X E
This appendix contains a list of acronyms and a glossary of key terms used in the UAS
industry. Most of the acronyms and key terms were taken from the FAA or the U.S. military.
When an acronym or term was taken from another source it is noted accordingly. The lists
include some acronyms and terms not used in the primer but may be of interest to the air-
port operator introducing UAS operations to the airport. The intent is to be as inclusive as
reasonably possible.
E-1 Acronyms
ACâadvisory circular
ADSâBâautomatic dependent surveillanceâbroadcast. The FAA air traffic organization
describes ADS-B as follows:
â¢ Automatic
â Periodically transmits information with no pilot or operator input required
â¢ Dependent
â Position and velocity vector are derived from the global positioning system (GPS) or a flight
management system (FMS)
â¢ Surveillance
â A method of determining position of aircraft, vehicles, or other assets
â¢ Broadcast
â Transmitted information available to anyone with the appropriate receiving equipment
ARCâAviation Rulemaking Committee
ASTMâAmerican Society of Testing and Materials (formerly)
AUVSIâAssociation of Unmanned Vehicle Systems International: The worldâs largest nonprofit
organization devoted exclusively to advancing the unmanned systems and robotics community.
Serving more than 7,500 members from government organizations, industry, and academia,
AUVSI is committed to fostering, developing, and promoting unmanned systems and robotic
technologies. AUVSI members support defense, civil, and commercial sectors.
AVâair vehicle: Synonymous with UAS.
AVOâair vehicle operator: Synonymous with pilot-in-command (PIC).
BLOSâbeyond line-of-sight: A term often used by the military to describe radio communica-
tions capabilities that link personnel or systems which are too distant or too fully obscured by
terrain for line-of-sight (LOS) communications. Some UAS are able to travel outside of LOS
Acronyms and Glossary
of Key Terms

E-2 Unmanned Aircraft Systems (UAS) at Airports: A Primer
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and use a satellite link to transmit and receive signals to or from the GCS. The civilian industry
also uses the terms BVLOSâBeyond Visual LOS and BRLOSâBeyond Radio LOS.
BWâbandwidth: The width of the range (or band) of frequencies that an electronic signal uses
on a given transmission. BW with regard to computers is the rate of data transfer, or bit rate
throughput. This is what controls the amount of data that can be uplinked and downlinked to
or from a UAS.
CASAâCivil Aviation Safety Authority
CFRâCode of Federal Regulations
CLâcommand link: When controlling the UAS in Ku-band, the CL is the package of informa-
tion sent to the aircraft from the GCS to control it. The CL can also be sent in other parts of the
electromagnetic spectrum.
CNSâcommunication, navigation, and surveillance
COAâCertificate of Waiver or Authorization: Authorization to operate a UAS for non-
recreational purposes in the United States. COAs are limited to public UAS operations. The FAA
approves and authorizes a COA.
CPAâconventionally piloted aircraft
CRâclose range: Category of UAS able to fly up to 10,000 feet for 2 to 4 hours with an operating
range of 5 to 10 miles (military exclusive term).
DAAâdetect-and-avoid: Term used instead of sense and avoid in the Terms of Reference for
the Radio Technical Commission for Aeronautics (RTCA) Special Committee 228. This new
term has not been defined by RTCA and may be considered to have the same definition as sense
and avoid when used.
DALâdesign assurance level
DLTV/DTVâdaylight television sensor which can be installed on a UAS and operates in the
visible region of the electromagnetic spectrum.
DODâU.S. Department of Defense
EASAâEuropean Aviation Safety Agency
ECUâEnvironmental Control Unit: Used to control and regulate the inside of the GCA
to protect sensitive electronic equipment and allow a comfortable environment for the
crew.
EO/IRâelectro optical/infrared: Sensor which operates in the visible and/or infrared regions of
the electromagnetic spectrum.
EPâexternal pilot: Refers to a pilot who controls an aircraft but is not actually on board.
A UAS pilot controls the aircraft from a GCS and is referred to as an external pilot. GCS
as used here includes hand-held transmitters used by an external pilot using VLOS
procedures.
FAAâFederal Aviation Administration
FGCSâfixed ground control station: A military term synonymous with GCS which refers to
the UAS control center, housed in a customer-furnished building, used to control one or more
UASs. The FGCS is designed primarily for mission control element (MCE) remote operations
via a Satellite Communications (SATCOM) data-link.

Acronyms and Glossary of Key Terms E-3
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FLIRâforward looking infrared: A passive imaging system that senses infrared radiation. The
wavelength of infrared that thermal imaging cameras detect differs significantly from that of
night vision, which operates in the visible light and near-infrared ranges. (Older USAF Term)
FMRAâFAA Modernization and Reform Act of 2012 (H.R. 658): The law passed to assist with
modernizing the nationâs aviation system. The law provides funding for the modernization ATC
system and allows the FAA to rebuild its ATC system to the next generation technology which
will include switching from radar to a GPS ATC system.
FOVâfield of view: The extent of the observable world that is seen at any given moment from
a sensor onboard the UAS. Depending on the sensor and the camera/display used, there can be
more than one FOV.
GAOâGeneral Accounting Office
GCSâground control station: The station that UAS crews use to control the air vehicle and
operate the sensors and systems on board. These stations are sometimes fixed in an office-sized
room, and feature a number of computer systems to monitor and control the aircraft. However,
GCS may also be an outside location with no enclosure depending on the type of UAS operation.
There are also deployable versions of GCSs, meant to be the size and shape of standard shipping
containers that can easily fit into a cargo aircraft for transportation.
GDTâground data terminal: Set of antennas and integrated systems that allow a data-link
between the GCS and air vehicle to control and receive feedback and video from the aircraft.
HALEâhigh altitude, long endurance: A method of classification which classifies UASs in
groups based on capabilities. Military HALE vehicles are described as vehicles able to fly above
30,000 feet for more than 24 hours with an operating range over 1,000 nautical miles.
HDDâhead down display: Monitors usually located underneath the head up display (HUD) to
display engine parameters, link status, electrical load, fuel levels, etc. HDD is any display which
is not a HUD.
HUDâhead up display: Display projected on the pilot/system operator monitors to allow the
operator to fly the UAS. All of the essential information such as altitude, airspeed, attitude, and
more are displayed in the HUD. Flying the vehicle can also be accomplished through HDD or
Visual LOS (VLOS) control.
ICAOâInternational Civil Aviation Organization
ILLAâinitial lost link altitude: Preprogrammed altitude used in the case of lost data-link
between the GCS and the aircraft. If the link is lost, the UAS will automatically assume this
altitude and follow preprogrammed contingency procedures awaiting a returned link with
the GCS.
ILLHâinitial lost link heading: Preprogrammed heading used in the case of lost link between
the GCS and the aircraft. If the link is lost, the UAS will automatically assume this heading
and follow preprogrammed contingency procedures awaiting a returned link with the GCS.
LALEâlow altitude long endurance: A method of classification which classifies UASs in groups
based on capabilities. Military LALE vehicles are defined as UASs able to fly up to 10,000 ft. for
more than 24 hrs. with an operating range over 200 NM.
LIDARâlight detection and ranging: A remote sensing method that uses light in the form of a
pulsed laser to measure ranges (variable distances) to the Earth. These light pulsesâcombined
with other data recorded by the airborne systemâgenerate precise, three-dimensional informa-
tion about the shape of the Earth and its surface characteristics. (NOAA 2014)

E-4 Unmanned Aircraft Systems (UAS) at Airports: A Primer
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LL/LL-LOSâloss of link or lost link line-of-sight: A break in connection or loss of connection
between the commands given in the GCS and the ability for the UAS to receive and respond to
those commands.
LLTVâlow light television: A vidicon tube with multiplier tubes that gives a useful picture in
near darkness. The system has an excellent night optical capability. This sensor is used mainly
to get useful pictures around sunset or sunrise when there is not enough light for a DAY TV and
too much for an IR camera.
LOSâline-of-sight: This describes the data-link method of controlling the aircraft. LOS control
is often higher quality with direct control and feedback, versus BLOS control which is often
accomplished via satellite link and may have a delay. Critical phases of flight, takeoffs, and land-
ings are mostly performed using LOS link for small UAS. To be even more specific, there is
visual line-of-sight (VLOS) and Radio Line-of-Sight (RLOS). VLOS provides the opportunity
for direct control and feedback. The major difference between VLOS/RLOS and BLOS is higher
bandwidth and lower latencies.
LREâlaunch and recovery element: The LRE consists of the crews that are responsible for ini-
tiating flight and recovering the aircraft. The military refers to it in the following manner: LRE
crews are typically experienced mission control element (MCE) crews, as this is treated like an
âupgradeâ in Air Force UAS programs. The LRE is responsible for the preflight walk-around
inspection, landing, taxiing back, and shutting down. The only phase of flight the LRE is gener-
ally not responsible for is the mission phase, which is covered by the MCE after âhanding-overâ
control of the aircraft at a predetermined location in air. The LRE is also capable of conducting
local line-of-site missions.
LRSâlaunch and recovery site: The LRS is the site where all of the systems are deployed and all
the manpower and equipment are located. Most of the time, this is also where maintenance on
the system is performed. Many UAS takeoff and land at an LRS in the same manner as manned
aircraft at a runway.
MALEâmedium altitude, long endurance: A method of classification that classifies UASs
in groups based on capabilities. Military MALE UAS are defined as vehicles able to fly above
20,000 feet, for more than 24 hours, and with an operating range over 200 nautical miles.
MCEâmission control element: For some UAS, the MCE consists of the crews that are respon-
sible for everything outside of the launch and recovery of the aircraft. (MCE is a term used by
the military. Most likely the civil growth of UAS will occur in the use of smaller UAS initially;
the term may be used or changed as the civil UAS industry grows.)
MPCSâmission planning and control site: Site where the aircraft is controlled during its mis-
sion. The MPCS may or may not be collocated with the LRS.
MRâmedium range: A category of UAS used by some organizations to designate an aircraft
able to fly up to 15,000 feet, for 4 to 8 hours, and with an operating range up to 100 nautical
miles.
NASâNational Airspace System: The common network of U.S. airspace; air navigation facili-
ties, equipment, and services, airports or landing areas; aeronautical charts, information, and
services; rules, regulations, and procedures; technical information; and manpower and material.
Included in the NAS are system components shared jointly with the military.
NASAâNational Aeronautics and Space Administration
OPAâoptionally piloted aircraft: An aircraft that is integrated with UAS technology and still
retains the capability of being flown by an onboard pilot using conventional control methods.

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Pfâprobability of failure
P/SOWâpilot/sensor operator workstation: Control station inside the GCS from where the
pilot or system operator is operating the UAS and its onboard systems and sensors.
PCMâprimary control module: The brain of a UAS which processes all the information
received and transmitted to the aircraft.
PGCSâportable ground control station: A smaller GCS that can fit into a few suitcases and be
set up in a tactical environment or on top of a desk.
PGDTâportable ground data terminal: Same definition as GDT, sometimes smaller in size to
allow for ease of transport and to be easily set up in a remote environment.
PICâpilot-in-command: Crewmember responsible for actual flight of the UAS; additional
roles will differ with individual UAS capabilities and missions. All UAS operating in the NAS
must have a PIC. PIC is the person who:
â¢ Has final authority and responsibility for the operation and safety of the flight;
â¢ Has been designated as PIC before or during the flight; and
â¢ Holds the appropriate category, class, and type rating, if appropriate, for the conduct of the
flight. PIC is a term used by the military. Most likely the civil growth of UAS will occur in the
use of smaller UAS initially; the term may be used or changed as the civil UAS industry grows.
RLâreturn link: When controlling the UAS, the RL is the package of information sent from the
aircraft to the GCS containing pictures and metadata.
RLOSâradio line-of-sight
ROAâremotely operated aircraft
RPAâremotely piloted aircraft
RPASâRemotely Piloted Aircraft System
RPVâremotely piloted vehicle. ROA, RPA, RPAS, and RPV are all used synonymously for an
aircraft which is unmanned. ROA and RPV are no longer used in most segments of the industry.
RSOâremote split operations: RSO are conducted when the LRS and the MPCS are not col-
located. Some UAS are equipped with SATCOM, and missions can extend beyond line-of-sight
or over the horizon. These missions are flown from a geographically separated, or remote, GCS.
When conducting RSO, the LRS will launch the aircraft and hand over controls to the MPCS
at a predetermined point in the air. Upon mission completion, the MPCS will then return the
aircraft to a predetermined location where the LRS will take control and land the aircraft.
SAAâsense and avoid: The capability of a UAS to remain well clear from and avoid collisions
with other airborne traffic. Sense and avoid provides the functions of self-separation and col-
lision avoidance to establish an analogous capability to âsee and avoidâ required by manned
aircraft.
sUASâSmall Unmanned Aircraft System: An unmanned aircraft weighing less than 55 pounds
and operated within VLOS below 400 feet. Other restrictions also apply.
SOâsensor operator: The SO, if required, is primarily responsible for the operation of the UAS
payload. Additionally, this crewmember is responsible for backing up the pilot/operator on mon-
itoring aircraft engine, electrical, and data-link systems during most phases of flight. The SO is
also responsible for reading checklists to the pilot in normal and emergency situations. The SO
primarily focuses on mission executionâtracking targets and reporting with other agencies on

E-6 Unmanned Aircraft Systems (UAS) at Airports: A Primer
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information, intelligence, and surveillance findings; and monitoring flight path for de-confliction
with weather, terrain, and other aircraft during the MCE phase. SO is a term used by the military.
Most likely the civil growth of UAS will occur in the use of smaller UAS initially; the term may be
used or changed as the civil UAS industry grows.
UAâunmanned aircraft:
â¢ A device used or intended to be used for flight in the air that has no onboard pilot. This
device excludes missiles, weapons, or exploding warheads, but includes all classes of airplanes,
helicopters, airships, and powered-lift aircraft without an onboard pilot. UA do not include
traditional balloons (see 14 CFR Part 101), rockets, tethered aircraft, and unpowered gliders.
â¢ An aircraft that is operated without the possibility of direct human intervention from within
or on the aircraft.
UASâUnmanned Aircraft System: An unmanned aircraft and its associated elements related to
safe operations, which may include control stations (ground, ship, or air-based), control links,
support equipment, payloads, flight termination systems, and launch/recovery equipment.
An unmanned aircraft and associated elements (including communications links and the
components that control the unmanned aircraft) those are required for the PIC to operate safely
and efficiently in the NAS.
UAVâunmanned aerial vehicle: An unmanned aerial vehicle, commonly known as a drone, is
an aircraft without a human pilot on board. Its flight is controlled either by computers in the
vehicle, or under the remote control of a pilot on the ground or in another vehicle. There are a
wide variety of drone shapes, sizes, configurations, and characteristics. Historically, UAVs were
simple RPA, but onboard control is increasingly being employed. (Note: this term is no longer
widely used in the industry; however, when searching for information on unmanned aircraft, using
UAV may still lead to useful information.)
ULâup link: UL is the package of information sent to the aircraft from the GCS to control it.
UMSâUnmanned System
UVSIâUnmanned Vehicle Systems International
VLOSâvisual line-of-sight
E-2 Glossary of Key Terms
Autonomous FlightâSet of equipment/computers, and internal navigation systems (INS) GPS
navigation units which allow a UAS to navigate and fly autonomously. Autonomous flight gener-
ally means the vehicle is capable of reasoning and decision making without oversight or interven-
tion from human controllers, a level of autonomy that is not presently contained in most UAS.
C-BandâFrequency band selected and used by a UAS system to operate an aircraft from its
control station when in line-of-sight. C-Band is from 4GHz to 8GHz and is one of several bands
used to control UAS.
Civil AircraftâAircraft other than public aircraft (public aircraft include military and other
government-use aircraft). Civil aircraft include those which are privately owned such as general
aviation (GA) aircraft governed by 14 CFR Part 91, and those operated for commercial purposes
such as those which fall under 14 CFR Part 121 and 14 CFR Part 135 operations.
Class A AirspaceâGenerally, airspace from 18,000 feet MSL up to and including FL 600, including
the airspace overlying the waters within 12 nautical miles of the coast of the 48 contiguous states of

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the United States and Alaska. Unless otherwise authorized, all persons must operate their aircraft
under Instrument Flight Rules (IFR) in Class A airspace.
Class B AirspaceâGenerally, airspace from the surface to 10,000 feet MSL surrounding the
nationâs busiest airports having very high numbers of airport operations or passenger enplane-
ments. The configuration of each Class B airspace area is individually tailored and consists of a
surface area and two or more layers (some Class B airspace areas resemble upside-down wed-
ding cakes), and is designed to contain all published instrument procedures once an aircraft
enters the airspace. An ATC clearance and two-way communication is required for all aircraft
to operate in the area, and all aircraft that are so cleared receive separation instructions within
the airspace.
Class C AirspaceâGenerally, that airspace from the surface to 4,000 feet above the airport
elevation surrounding those airports that have an operational control tower, are serviced by
a radar approach control, and have a certain number of IFR operations or passenger enplane-
ments. Although the configuration of each Class C area is individually tailored, the airspace usu-
ally consists of a surface area with a five nautical mile (NM) radius, a circle with a 10 NM radius
that extends no lower than 1,200 feet up to 4,000 feet above the airport elevation, and an outer
area that is not charted. Each person must establish two-way radio communications with the
ATC facility providing air traffic services prior to entering the airspace, and thereafter maintain
those communications while within the airspace.
Class D AirspaceâGenerally, airspace from the surface to 2,500 feet above the airport elevation
surrounding those airports that have an operational control tower. The configuration of each
Class D airspace area is individually tailored and when instrument procedures are published
and the airspace will normally be designed to contain the procedures. Arrival extensions for
instrument approach procedures may be within Class D or Class E airspace. Unless otherwise
authorized, each person must establish two-way radio communications with the ATC facility
providing air traffic services prior to entering the airspace and thereafter maintain those com-
munications while in the airspace.
Class E AirspaceâGenerally, if the airspace is not Class A, Class B, Class C, or Class D, and it is
controlled airspace, it is Class E airspace. Class E airspace extends upward from either the surface
or a designated altitude to the overlying or adjacent controlled airspace. When designated as a
surface area, the airspace will be configured to contain all instrument procedures. Also in this
class are federal airways, airspace beginning at either 700 or 1,200 feet AGL used to transition
to/from the terminal or en route environment, en route domestic, and offshore airspace areas
designated below 18,000 feet MSL. Unless designated at a lower altitude, Class E airspace begins
at 14,500 MSL over the United States, including that airspace overlying the waters within 12 NMs
of the coast of the 48 contiguous states and Alaska, up to, but not including 18,000 feet MSL,
and the airspace above FL 600.
Class G AirspaceâThat airspace not designated as Class A, B, C, D or E.
Note for Airspace definitions: There are also minimum equipment requirements for aircraft to operate
in each class of airspace. This in many ways can be a limiting factor to UAS operators. (FAA 2014d)
Collision AvoidanceâThe sense and avoid (detect-and-avoid) system function where the
UAS takes appropriate action to prevent an intruder from penetrating the collision volume.
Action is expected to be initiated within a relatively short time horizon before the closest point
of approach. The collision avoidance function engages when all other modes of separation fail.
(See SAA; see DAA)
Communication LinkâThe voice or data relay of instructions or information between the UAS
pilot and the ATC and other NAS users. It is generally understood that there are two possible

E-8 Unmanned Aircraft Systems (UAS) at Airports: A Primer
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communication links; one from the UAS operator to/from the vehicle and the other from the
payload operator to/from the vehicle.
Control StationâThe equipment used to maintain control, communicate with, guide, or other-
wise pilot an unmanned aircraft. The control station includes the communications equipment,
computers, control inceptors, and displays used to control the vehicle as well as the physical
enclosure, support systems, and power sources.
Crewmember [UAS]âIn addition to the crewmembers identified in 14 CFR Part 1, a UAS flight
crewmember includes pilots, sensor/payload operators, and visual observers, but may include
other persons as appropriate or required to ensure safe operation of the aircraft.
Data-linkâTypically, a ground-to-air communications system that transmits information
via digital coded pulses. However, data-link can also be air-to-air, ground-to-ground, and
ground-to-space.
Lost LinkâDescribes the state of the aircraft when it has no communication with ground
control. Once the link is lost, the operator is no longer in control of the airplane until link is
regained. In the event of lost link, the UAS executes preprogrammed lost link procedures, which
can be loaded prior to takeoff or during flight depending on the type of UAS. The aircraft will
strictly follow the procedures preprogrammed by the operator. A few examples of lost link
procedures are listed below:
â¢ Fly to the recovery field
â¢ Fly to a specific set of coordinates using GPS
â¢ Take any action it was preprogrammed to take (such as flight termination).
Model AircraftâAn unmanned aircraft that is capable of sustained flight in the atmosphere;
flown within visual line-of-sight of the person operating the aircraft, and flown for hobby or
recreational purposes.
Narrow Beam AntennaâHigh gain antenna with a focused narrow sector for a long distance.
OMNI AntennaâOmnidirectional antenna that sends and receives signals equally in all directions.
OperatorâUnder the proposed FAA rule for small UAS, pilots of a small UAS will be considered
operators.
PayloadâSet of sensors and cameras carried on board a UAS.
Public AircraftâAn aircraft operated by a governmental entity (including federal, state, or local
governments, and the U.S. DOD and its military branches) for certain purposes as described in
49 U.S.C. Â§Â§ 40102(a)(41) and 40125. Public aircraft status is determined on an operation by
operation basis. See 14 CFR Part 1, Â§ 1.1 for a complete definition of a public aircraft.
Public AviationâPublic Aircraft Operation (PAO) is limited by statute to certain government
operations within U.S. airspace. Although these operations must comply with certain general
operating rules (including those applicable to all aircraft in the NAS), other civil certification
and safety oversight regulations do not apply. Whether or not an operation may be considered
public is determined on a flight-by-flight basis, under the terms of the statute (49 U.S.C. 40102
and 49 U.S.C. 40125) and depends on factors such as aircraft ownership, operator, the purpose
of the flight, and the persons on board the aircraft.
SATCOMâSatellite communications: Term used to describe controlling the aircraft in BLOS
using a satellite system and equipment.
Section 333 ExemptionâBy law, any aircraft operation in the national airspace requires a cer-
tificated and registered aircraft, a licensed pilot, and operational approval. Section 333 of the

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FAA Modernization and Reform Act of 2012 grants the Secretary of Transportation the authority
to determine whether an airworthiness certificate is required for a UAS to operate safely in the
NAS. This authority is being leveraged to grant case-by-case authorization for certain unmanned
aircraft to perform commercial operations prior to the finalization of the Small UAS Rule, which
will be the primary method for authorizing small UAS operations once it is complete. The Sec-
tion 333 Exemption process provides operators who wish to pursue safe and legal entry into the
NAS a competitive advantage in the UAS marketplace, thus discouraging illegal operations and
improving safety.
Self-SeparationâSense and avoid system function where the UAS maneuvers within a suffi-
cient timeframe to remain clear of other airborne traffic.
SensorâSet of equipment that can be installed on board the UAS for the purpose of informa-
tion gathering.
Special Airworthiness CertificateâExperimental Category (UAS)âAirworthiness certification
for a civil experimental UAS. The FAA defines the Experimental Category as follows: A special
airworthiness certificate in the experimental category is issued to operate an aircraft that does
not have a type certificate or does not conform to its type certificate and is in a condition for safe
operation. Additionally, this certificate is issued to operate a primary category kit-built aircraft
that was assembled without the supervision and quality control of the production certificate
holder.
Test RangeâA defined geographic area where research and development are conducted. Test
ranges are also known as test sites in related documents, such as the FAAâs Screening Informa-
tion Request.
Visual Line-of-SightâUnaided (corrective lenses and/or sunglasses exempted) visual contact
between a pilot-in-command or a visual observer and a UAS sufficient to maintain safe opera-
tional control of the aircraft, know its location, and be able to scan the airspace in which it is
operating to see and avoid other air traffic or objects aloft or on the ground.
Wide AntennaâDirectional antenna, perhaps on a UAS ground data terminal, which sends
and receives signals equally distributed in a wide sector of interest with a variety of ranges that
are specific to the operation.

TRB’s Airport Cooperative Research Program (ACRP) Report 144: Unmanned Aircraft Systems (UAS) at Airports: A Primer provides airports of all sizes with information about unmanned aircraft systems (UAS) and their potential use and impact on airports. The report includes a glossary of key terms, a background on the current state of UAS operations, UAS costs and benefits to airports, regulatory and community considerations, UAS infrastructure and operational considerations, UAS safety and security issues, and more.

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